The TDA7294 high-efficiency circuit is actually a Class-G output stage with dual rail pairs, a low pair at +/- 20V and a high pair at +/- 40V. It is worth reading and understanding Class-G operation before attempting this circuit. Douglas Self's book has a chapter and example discrete bipolar circuit for Class-G operation, but the principles are the same here.

The basic TDA7294 circuit (non-bridged) is simple and reliable - there are numerous tweaks to it in various gainclone threads on this forum. I would strongly recommend it as an excellent first DIY amplifier project.

The TDA7294 is available at Modern Electronics (off S.P. Road) for Rs.85, and the basic circuit PCB is available at Om Electronics for Rs.20. You'll need two each for dual-channel (stereo) operation.

The entire assembled module is also available for Rs.180, but I'd advise buying the bare PCB, IC, passives, etc. and assembling it - this allows the use of premium capacitors, components, etc.

In electrolytic capacitors: Elna, Panasonic, Nippon Chemicon, Rubycon, Nichicon, Sanyo. Specific series have specific properties - some are good in the signal path, some only for supply filtering and bypass. They're not always available in the desired values. The premium types like Cerafine, Black Gates, Silmic IIs, etc are pretty much unobtainium, and are likely to be counterfeits. I've found Panasonic FC (which is the best inexpensive electrolytic for just about any audio application) and FJ from time to time. Elna ROS can be hard to find, except some occasional surplus items. Elna RJH and RJ4 show up from time to time, and they're OK for supply filtering/bypass.

In polypropylene: Wima - hard to find.

In film/mylar: Vishay, Philips are OK.

In most other types: brand doesn't really matter. Silver Mica is preferred for some small values related to compensation/stability. Ceramics are to avoided in the signal path.

Toroidal transformers: Salzer, Miracle (both are made to order)

E-I transformers: brand probably doesn't matter as long as it meets specs.

Metal film resistors: Dale, Vishay is OK - any 1% tolerance type should be OK. Carbon-film should be avoided unless that value is unavailable in metal film.

They are there in Bangalore, but you may have to pay through your nose or buy in quantity. RS Components will sell retail quantities, but marked up hugely. Arrow and Future Electronics are wholesale distributors, and will only sell in volume. You probably can't economically build DIY prototypes with parts sourced this way.

For DIY, you best bets are the traditional electronics bazaars like Ritchie Street, Lamington Road, S.P. Road, etc., where you can buy single-unit quantities of parts with only a small markup to wholesale.